Golf ball with vapor barrier layer and method of making same

ABSTRACT

A golf ball with at least one moisture vapor barrier layer is disclosed. In accordance to one aspect of the invention, the moisture vapor barrier layer may comprise butyl rubber. The butyl rubber may also be a halogenated butyl rubber such as bromobutyl rubber or chlorobutyl rubber. The butyl rubber may also be a sulfonated butyl rubber. The butyl rubber may be blended with other polymers. In accordance to another aspect of the invention, the moisture vapor barrier layer is placed on to a core subassembly and cured by infrared radiation (IR). IR-curable moisture vapor barrier materials include, but not limited to, butyl rubber, polysulfide rubber and single-pack castable polymers, among others. In accordance to another aspect of the invention, an outer layer of the golf ball may comprise a polymer that has a cured temperature greater than the softening temperature or melting temperature of the encased subassembly. Such outer layer may be cured by IR. The outer layer may be a cover, an intermediate layer or a moisture vapor barrier layer.

STATEMENT OF RELATED PATENT APPLICATION

This non-provisional utility patent application is a continuation ofU.S. patent application Ser. No. 10/754,781, filed Jan. 9, 2004, nowU.S. Pat. No. 6,932,720 which is a continuation of U.S. patentapplication Ser. No. 10/103,414, filed on Mar. 21, 2002, now abandonedwhich is a continuation-in-part of U.S. patent application Ser. No.09/973,342, filed on Oct. 9, 2001, now U.S. Pat. No. 6,632,147. Theparent applications and patent are hereby incorporated by reference intheir entirety.

FIELD OF THE INVENTION

The present invention relates to a novel structure for a golf ball, andmore particularly to a golf ball with a moisture vapor barrier layer.

BACKGROUND OF THE INVENTION

Solid core golf balls are well known in the art. Typically, the core ismade from polybutadiene rubber material, which provides the primarysource of resiliency for the golf ball. U.S. Pat. Nos. 3,241,834 and3,313,545 disclose the early work in polybutadiene chemistry. It is alsoknown in the art that increasing the cross-link density of polybutadienecan increase the resiliency of the core. The core is typically protectedby a cover from repeated impacts from golf clubs. The golf ball maycomprise additional layers, which can be an outer core or an inner coverlayer. One or more of these additional layers may be a wound layer ofstretched elastic windings to increase the ball's resiliency.

A known drawback of polybutadiene cores cross-linked with peroxideand/or zinc diacrylate is that this material is adversely affected bymoisture. Water moisture vapor reduces the resiliency of the cores anddegrades its properties. A polybutadiene core will absorb water andloose its resilience. Thus, these cores must be covered quickly tomaintain optimum ball properties. The cover is typically made fromionomer resins, balata, and urethane, among other materials. The ionomercovers, particularly the harder ionomers, offer some protection againstthe penetration of water vapor. However, it is more difficult to controlor impart spin to balls with hard covers. Conventional urethane covers,on the other hand, while providing better ball control, offer lessresistance to water vapor than ionomer covers.

Prolonged exposure to high humidity and elevated temperature may besufficient to allow water vapor to invade the cores of some commerciallyavailable golf balls. For example at 110° F. and 90% humidity for asixty day period, significant amounts of moisture enter the cores andreduce the initial velocity of the balls by 1.8 ft/s to 4.0 ft/s orgreater. The change in compression may vary from 5 PGA to about 10 PGAor greater. The absorbed water vapor also reduces the coefficient ofrestitution (CoR) of the ball.

Several prior patents have addressed the water vapor absorption problem.U.S. Pat. No. 5,820,488 discloses a golf ball with a solid inner core,an outer core and a water vapor barrier layer disposed therebetween. Thewater vapor barrier layer preferably has a water vapor transmission ratelower than that of the cover layer. The water vapor barrier layer can bea polyvinylidene chloride (PVDC) layer. It can also be formed by an insitu reaction between a barrier-forming material and the outer surfaceof the core. Alternatively, the water vapor barrier layer can be avermiculite layer. U.S. Pat. Nos. 5,885,172 and 6,132,324 disclose,among other things, a golf ball with a polybutadiene or wound core withan ionomer resin inner cover and a relatively soft outer cover. The hardionomer inner cover offers some resistance to water vapor penetrationand the soft outer cover provides the desirable ball control.Additionally, U.S. Pat. No. 5,875,891 discloses an impermeable packagingfor golf balls. The impermeable packaging acts as a moisture barrier tolimit moisture absorption by golf balls during storage, but not duringuse.

The moisture vapor barrier layer disclosed in the prior patents can berigid and makes the ball stiffer. Furthermore, producing a rigid layermay cause significant production obstacles. On the other hand, lessrigid polymers, such as butyl rubber and other rubbers, are known tohave low permeability to air, gases and moisture. Butyl rubber is widelyused as sealant for rooftops, as inner liner in tubeless tires, and aslining for chemical tanks, among other uses. In the golf ball art, butylrubber's usage has been limited to practice balls or driving range ballsdue to its slow initial velocity and low CoR, as discussed in U.S. Pat.Nos. 5,209,485 and 4,995,613. Butyl rubber is also used as the outermostcover layer or a part of the cover due to its durability, as disclosedin U.S. Pat. Nos. 5,873,796 and 5,882,567, among others. However, themoisture vapor barrier advantage of butyl rubber has not heretofore beenutilized in the golf ball art to make a better performing golf ball.

Also, high-temperature curing of certain polymeric materials to form thewater vapor barrier layer or other outer layers on the golf ball isdifficult to accomplish, since such curing or crosslinking heats theentire golf ball subassembly. This heating method may degrade theuntargeted components or layers within the subassembly. Additionally,this curing method limits suitable outer layer materials to materialshaving a cured temperature that is lower than the softening temperatureor lower melting temperature of the inner layers or core.

Hence, there remains a need for a golf ball with an improved water vaporbarrier layer and improved methods for applying a water vapor barrierlayer on to the core of the golf ball.

SUMMARY OF THE INVENTION

The present invention is directed to a golf ball comprising a layer ofmoisture vapor barrier with a moisture vapor transmission ratepreferably lower than that of the cover. Preferably, the moisture vaporbarrier layer comprises butyl rubber. The butyl rubber may also be ahalogenated butyl rubber such as bromobutyl rubber or chlorobutylrubber. The butyl rubber may also be a sulfonated butyl rubber. Thebutyl rubber may be blended with other polymers, such as doublebond-vulcanizable rubber, ethylene propylene diene monomer rubber andvinylidene chloride.

The present invention is also directed to a golf ball comprising amoisture vapor barrier layer, which comprises copolymer of isobutyleneand p-methylstyrene or polyisobutylene.

In accordance to another aspect of the invention, the moisture vaporbarrier layer is placed on to a core subassembly and cured by infraredradiation (IR). IR-curable moisture vapor barrier materials include, butnot limited to, butyl rubber, polysulfide rubber and single-packcastable polymers, among others.

In accordance to another aspect of the invention, an outer layer of thegolf ball may comprise a polymer that has a cured temperature greaterthan the softening temperature or melting temperature of the encasedsubassembly. Such outer layer may be cured by IR. The outer layer may bea cover, an intermediate layer or a moisture vapor barrier layer.

The present invention is also directed to a golf ball comprising a butylrubber moisture vapor barrier and a relatively soft cover. Preferably,the soft cover has a Shore D of less than 65 or between about 30 andabout 60, and more preferably between about 35 and about 50, and mostpreferably about 40 and about 45. The cover preferably has a thicknessof between about 0.010 inch to about 0.050 inch, and more preferablyabout 0.030 inch. The cover preferably comprises a thermoset polymer.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings which form a part of the specification andare to be read in conjunction therewith and in which like referencenumerals are used to indicate like parts in the various views:

FIG. 1 is a front view of a dimpled golf ball in accordance to thepresent invention;

FIG. 2 is a cross-sectional view of the golf ball in FIG. 1 showing asolid core surrounded by a thin moisture vapor barrier layer and acover; and

FIG. 3 is a cross-sectional view of another golf ball in accordance tothe present invention showing a solid core with multiple wound layerssurrounded by a thin moisture vapor barrier layer.

DETAILED DESCRIPTION OF THE INVENTION

As shown generally in FIGS. 1 and 2, where like numbers designate likeparts, reference number 10 broadly designates a golf ball in accordanceto the present invention. Golf ball 10 preferably has a solid core 12,an intermediate layer 14 and a cover 16. Solid core 12 may comprise asingle spherical element, or it may comprise a spherical element withone or more intermediate layers surrounding the spherical element. Solidcore 12 can be made from any suitable core materials including thermosetplastics, such as natural rubber, polybutadiene (PBD), polyisoprene,styrene-butadiene or styrene-propylene-diene rubber, and thermoplasticssuch as ionomer resins, polyamides, polyesters, or a thermoplasticelastomer. Suitable thermoplastic elastomers include Pebax®, which isbelieved to comprise polyether amide copolymers, Hytrel®, which isbelieved to comprise polyether ester copolymers, thermoplastic urethane,and Kraton®, which is believed to comprise styrenic block copolymerselastomers. These products are commercially available from Elf-Atochem,E.I. Du Pont de Nemours and Company, various manufacturers, and ShellChemical Company, respectively. The core materials can also be formedfrom a castable material. Suitable castable materials include thosecomprising a urethane, polyurea, epoxy, silicone, IPN's, etc.

Additionally, suitable core materials may also include a reactioninjection molded polyurethane or polyurea, including those versionsreferred to as nucleated, where a gas, typically nitrogen, isincorporated via intensive agitation or mixing into at least onecomponent of the polyurethane, typically, the pre-polymer, prior tocomponent injection into a closed mold where essentially full reactiontakes place resulting in a cured polymer having reduced specificgravity. These materials are referred to as reaction injection molded(RIM) materials. Alternatively, the core may have a liquid center.

Cover 16 is preferably tough, cut-resistant, and selected fromconventional materials used as golf ball covers based on the desiredperformance characteristics. The cover may comprise one or more layers.Suitable cover materials include ionomer resins, such as Surlyn®available from DuPont, blends of ionomer resins, thermoplastic orthermoset urethane, acrylic acid, methacrylic acid, thermoplastic rubberpolymers consisting of block copolymers in which the elastomericmidblock of the molecule is an unsaturated rubber or a saturated olefinrubber, e.g., Kraton® rubbers available from Shell Chemical Co.,polyethylene, and synthetic or natural vulcanized rubber such as balata.

Additionally, other suitable core and cover materials are disclosed inU.S. Pat. No. 5,919,100 and international publications WO 00/23519 andWO 01/29129. These disclosures are incorporated by reference in theirentirety. Preferably, core 12 is made from a polybutadiene rubbermaterial and cover 16 is made from a composition comprising a thermosetor thermoplastic urethane or a composition comprising an ionomer resin.

To prevent or minimize the penetration of moisture, typically watervapor, into core 12 of golf ball 10, intermediate layer 14 comprises amoisture vapor barrier layer preferably disposed around core 12.Preferably, moisture vapor barrier layer 14 has a moisture vaportransmission rate that is lower than that of the cover, and morepreferably less than the moisture vapor transmission rate of an ionomerresin such as Surlyn® which is in the range of about 0.45 to about 0.95grams·mm/m²·day. Typically, the moisture vapor transmission rate ofionomer resin is less than 0.6 grams·mm/m²·day as reported in“Permeability and other Film Properties of Plastics and Elastomer”published by the Plastic Design Library (1995). The moisture vaportransmission rate is defined as the mass of moisture vapor that diffusesinto a material of a given thickness per unit area per unit time. Thepreferred standards of measuring the moisture vapor transmission rateinclude ASTM F1249-90 entitled “Standard Test Method for Water VaporTransmission Rate Through Plastic Film and Sheeting Using a ModulatedInfrared Sensor,” and ASTM F372-94 entitled “Standard Test Method forWater Vapor Transmission Rate of Flexible Barrier Materials Using anInfrared Detection Technique,” among others.

A preferred polymer for the moisture vapor barrier layer is butylrubber. Butyl rubber (IIR) is an elastomeric copolymer of isobutyleneand isoprene. Detailed discussions of butyl rubber are provided in U.S.Pat. Nos. 3,642,728, 2,356,128 and 3,099,644. The disclosures of thesereferences are incorporated herein by reference in their entireties.Butyl rubber is an amorphous, non-polar polymer with good oxidative andthermal stability, good permanent flexibility and high moisture and gasresistance. Generally, butyl rubber includes copolymers of about 70% to99.5% by weight of an isoolefin, which has about 4 to 7 carbon atoms,e.g., isobutylene, and about 0.5% to 30% by weight of a conjugatedmultiolefin, which has about 4 to 14 carbon atoms, e.g., isoprene. Theresulting copolymer contains about 85% to about 99.8% by weight ofcombined isoolefin and 0.2% to 15% of combined multiolefin. Commerciallyavailable butyl rubbers, such as those manufactured by ExxonMobilChemical Company, typically have about 1 to 2.5 mole percent ofisoprene. Butyl rubbers generally have molecular weight of about 20,000to about 500,000. Suitable butyl rubber is also available from UnitedCoatings under the tradename Elastron™ 858. Elastrom 858 is a butylrubber coating applied as a solution in a volatile hydrocarbon solvent,which is typically sprayed or dipped on to an object or a surface, andcontains lead peroxide as a crosslinking agent.

Butyl rubbers are also available in halogenated form. Halogenated butylrubbers may be prepared by halogenating butyl rubber in a solutioncontaining inert C3—C5 hydrocarbon solvent, such as pentane, hexane orheptane, and contacting this solution with a halogen gas for apredetermined amount of time, whereby halogenated butyl rubber and ahydrogen halide are formed. The halogenated butyl rubber copolymer maycontain up to one halogen atom per double bond. Halogenated butylrubbers or halobutyl rubbers include bromobutyl rubber, which maycontain up to 3% reactive bromine, and chlorobutyl rubber, which maycontain up to 3% reactive chlorine. Halogenated butyl rubbers are alsoavailable from ExxonMobil Chemical. Butyl rubbers and halogenatedrubbers advantageously have low permeability to air, gases and moisture.For example, as reported by the manufacturer the permeability ofnitrogen in butyl rubber is more than one order of magnitude less thanthat in neoprene, styrene butadiene rubber, natural rubber and nitrilebutadiene rubber.

Butyl rubber is also available in sulfonated form, such as thosedisclosed in the '728 patent and in U.S. Pat. No. 4,229,337. Generally,butyl rubber having a viscosity average molecular weight in the range ofabout 5,000 to 85,000 and a mole percent unsaturation of about 3% toabout 4% may be sulfonated with a sulfonating agent comprising a sulfurtrioxide (SO₃) donor in combination with a Lewis base containing oxygen,nitrogen or phosphorus. The Lewis base serves as a complexing agent forthe SO₃ donor. SO₃ donor includes compound containing available SO₃,such as chlorosulfonic acid, fluorosulfonic acid, sulfuric acid andoleum.

Typically, the moisture vapor transmission rate of butyl rubber is inthe range of about 0.001 to about 0.100 grams·mm/m²·day.

Other suitable moisture vapor barrier polymers include the elastomersthat combine the low permeability of butyl rubbers with theenvironmental and aging resistance of ethylene propylene diene monomerrubbers (EPDM), commercially available as Exxpro™ from ExxonMobilChemical. More specifically, these elastomers are brominated polymersderived from a copolymer of isobutylene (IB) and p-methylstyrene (PMS).Bromination selectively occurs on the PMS methyl group to providereactive benzylic bromine functionality. Another suitable moisture vaporbarrier polymer is copolymer of isobulyline and isoprene with a styreneblock copolymer branching agent to improve manufacturing processability.

Another suitable moisture vapor barrier polymer is polyisobutylene.Polyisobutylne is a homopolymer, which is produced by cationicpolymerization methods. Commercially available grades ofpolyisobutylene, under the tradename Vistanex™ also from ExxonMobilChemical, are highly paraffinic hydrocarbon polymers composed on longstraight chain molecules containing only chain-end olefinic bonds. Anadvantage of such elastomer is the combination of low permeability andchemical inertness to resist moisture vapor encroachment, and chemicalor oxidative attacks. Polyisobutylene is available as a viscous liquidor semi-solids, and can be dissolved in certain hydrocarbon solvents.

In accordance to another aspect of the invention, halogenated butylrubber can be blended with a second rubber, preferably a doublebond-vulcanizable rubber, in a specific mixing ratio in a two-stepkneading process and then cured to form a rubber blend that has lowair/vapor permeability and high adhesion to diene rubbers. A clearadvantage of this rubber blend is that it provides enhanced adherence toa polybutadiene core or subassembly to provide an enhancedmoisture/water vapor barrier layer. This rubber blend is discussed inU.S. Pat. No. 6,342,567 B2. The '567 patent is hereby incorporatedherein by reference. Alternatively, a brominatedisobutylene/p-methylstyrene, discussed above, can be used in place ofthe halogenated rubber. Other moisture vapor barrier polymers includethermoplastic elastomer blends that may be dynamically vulcanized andcomprise a butyl rubber or a halogenated butyl rubber, such as thosediscussed in U.S. Pat. Nos. 6,062,283, 6,334,919 B1 and 6,346,571 B1.These references are incorporated herein by reference. Alternatively,butyl rubber may be blended with a vinylidene chloride polymer, i.e.,saran, as disclosed in U.S. Pat. No. 4,239,799. The '799 patent is alsoincorporated herein by reference.

Butyl rubbers can be cured by a number of curing agents. Preferredcuring agents for golf ball usage include sulphur for butyl rubber, anda peroxide curing agent, preferably zinc oxide, for halogenated butylrubbers. Other suitable curing agents may include antimony oxide, leadoxide or lead peroxide. Lead based curing agents may be used whenappropriate safety precautions are implemented. Butyl rubbers arecommercially available in various grades from viscous liquid to solidswith varying the degree of unsaturation and molecular weights. Latexgrades are also available.

Butyl rubber and halogenated rubber can be processed by milling,calendering, extruding, injection molding and compression molding, amongother techniques. These processing techniques can produce a semi-curedsheets or half-shelves of the moisture vapor barrier material, which canbe wrapped around a core or a core subassembly. The moisture vaporbarrier can be fully cured by exposure to heat at elevated temperaturestypically in the range of about 250° F. to 2000° F.

Additionally, any number of fillers, additives, fibers and flakes, suchas mica, micaceous iron oxide, metal, ceramic, graphite, aluminum ormore preferably leafing aluminum, can be incorporated into the moisturevapor barrier layer to create a physical barrier, i.e., a more tortuouspath, against moisture vapor encroachment.

In accordance to another aspect of the invention, the curing of themoisture vapor barrier material on to the core or the core subassemblyis preferably accomplished by infrared radiation (IR). IR advantageouslyheats the moisture vapor material, e.g., butyl rubber, locally withoutpenetrating the underlying golf ball core and/or other encased layers.Hence, the predetermined properties of the core and/or of the encasedlayers would not be affected by the heating/curing of the moisture vaporbarrier layer. U.S. Pat. No. 6,174,388 B1 discloses that IR can be usedeffectively to heat and cure the surface of a polymeric object whileleaving the other portions of the object unchanged. U.S. Pat. Nos.5,677,362 and 5,672,393 disclose that IR heating can be used inconjunction with ultraviolet heating to cure polymers effectively. Thedisclosures of the patents are incorporated by reference in theirentirety.

Another advantage of using IR as the curing technique is that suitablemoisture vapor barrier polymers, which have cured or cross-linkingtemperatures that are higher than the softening temperature or themelting temperature of the materials encased therein, can be nowemployed as the moisture vapor barrier layer and/or other outer layers.

In accordance to another aspect of the present invention, anothersuitable IR-cured water vapor barrier material is polysulfide rubberincluding those disclosed in U.S. Pat. Nos. 4,263,078 and 4,165,425,among others. These references are incorporated herein by reference. Inone example, the polysulfide rubber is cured with lower alkyl tin oxide,such as di-n-butyl tin oxide, and used in hot applied processes asdisclosed in the '425 patent. This particular polysulfide rubber isthiol terminated and cured with the lower alkyl tin oxide attemperatures between 100° C. and 300° C. to become a solid thermoplasticelastomer that can be softened by heating and then cast or injectionmolded into a water vapor barrier layer. This polysulfide compound ispreferably cured by IR.

Another suitable IR-curable polysulfide rubber is based on thiolterminated liquid polysulfide polymer cured with zinc oxide and a sulfurcontaining compound selected from 2-mercaptobenzothiazol, zinc loweralkyl dithiocarbamate and alkyl thiuram polysulfides at temperaturesfrom about 200° F. to about 390° F. Agents, which improve the flowingproperties of the composition, such as copolymers of styrene andalkylenes, organic or inorganic reinforcing fibrous materials, phenolicresins, coumarone-indene resins, antioxidants, heat stabilizers,polyalkylene polymers, factice, terpene resins, terpene resins esters,benzothiazyl disulfide or diphenyl guanidine, can also be added to thecomposition. Advantageously, this polysulfide rubber possesses a goodability to wet the substrate and forms good bonds with such substratewhen cooled and, therefore, is a preferred sealant for the golf ballcore. This polysulfide compound is also preferably cured by IR.

Moisture vapor barrier layer comprising polysulfide rubber is fullydisclosed in co-pending patent application entitled “Golf Ball WithVapor Barrier Layer and Method for Making Same” filed on the same day asthe present application and assigned to the same assignee. Thedisclosure of this co-pending patent application is incorporated hereinby reference.

In accordance to another aspect of the present invention, suitableIR-cured water vapor barrier polymers include single-pack castablepolymers. A preferred single-pack polymer uses uretdiones or blockedisocyanates to form a single-pack urethane component. The single-packblocked isocyanate system, which preferably comprises isocyanatecombined with an amine or poloyl, is advantageously stable at roomtemperature. The application of heat, such as infrared radiation, causesthe isocyanate to become unblocked or to react to form a urethane. Nomixing or dynamically controlling the ratios of the components isrequired.

Uretdione castable materials can be pre-formulated as a single-packsystem without premature reaction. The mixed single-pack material can bedirectly injected or poured into a mold, avoiding metering and mixing ofmultiple components. Parts can be made utilizing viscous or solidmaterials that previously could not be used with traditional two-packsystems. Advantageously, uretdiones and blocked isocyanates whencombined with suitable reactive components can be milled into rubberstock for use with other manufacturing techniques, discussed above.

A non-limiting example of a single-pack system in accordance to thepresent invention is as follows. Finely ground uretdione is dispersed ina liquid polyol or polyamine in combination with a tin catalyst andcyclic amidine catalyst to form a slurry mixture. The slurry mixture ispoured into a suitable golf ball mold to make the required part, e.g.,core, intermediate layer or cover. The mold is then heated to reach thepredetermined deblocking temperature of about 150–180° C., and thereaction is allowed sufficient time to complete. The cured componentthen can be removed from the mold for further processing, if necessary.

In another example, 3,5-dimethylpyrazole (DMP) blocked IPDI is used inplace of the uretdione in the above example. The mold is then heated tothe deblocking temperature of about 140–160° C., and the reaction isallowed sufficient time to complete. In another non-limiting example,the single-pack moisture vapor barrier layer utilizes blockedisocyanates that volatilize when de-blocking occurs, such asdiethylmaleonate (DEM) or methyl ethyl ketoxime (MEKO) blockedhexamethylene diisocyanate cyclic trimer. Such an example could besprayed or dipped onto the golf ball core, subassembly or the like andthen followed with an IR cure.

Non-limiting chemical structures of the single-pack system are shownbelow: Formation of uretdiones:

Preferred chemical structure of polyuretdione cross-linker:

The preferred hardeners are uretdiones or blocked isocyanates, where theblocking agent remains in the component as a solid once cast, such asDMP or triazole blocked isocyanates. The structures of the preferredblocking agents are:

Single-pack castable water vapor barrier material is fully disclosed inparent application Ser. No. 09/973,342, which has been incorporated byreferenced.

In accordance to one aspect of the invention, the Shore D hardnessvalues for the core and moisture vapor barrier sub-assemblies have beenmeasured less than about 60 and more specifically in the range of about5–50. Alternatively, according to other aspects of the invention, themoisture barrier sub-assemblies may have Shore D hardness value ofgreater than 50, when more rigid materials, such as stiff ionomer with aShore D hardness of greater than 55 are used in conjunction with themoisture vapor barrier layer 14.

Preferably, a golf ball in accordance to the present invention comprisesa solid or multiple-layer solid polybutadiene core 12 having an outerdiameter of greater than about 1.50 inches, more preferably 1.550 inchesand most preferably about 1.580 inches. Moisture vapor barrier layer 14has a thickness preferably in the range of about 0.001 inch to about0.100 inch, more preferably in range of about 0.010 inch to about 0.050inch and cover 16 is a urethane cover with sufficient thickness toproduce a 1.680 inch diameter golf ball.

More preferably, the moisture vapor barrier layer is a thin layer ofsuitable butyl rubber polymers discussed above, preferably less than0.050 inch, more preferable less than 0.030 inch and most preferablyless than 0.010 inch. It is also preferable that the butyl rubbermoisture vapor barrier layer would not significantly and negativelyaffect the coefficient of restitution of the golf ball. Preferably, thepolybutadiene core 12 and the thin butyl rubber moisture vapor barrierlayer 14 are covered by a relatively soft polymer cover having athickness from about 0.010 to about 0.050 inch, more preferably about0.030 inch and has a Shore D of less than 65 or from about 30 to about60, more preferably from about 35 to about 50 and even more preferablyabout 40 to about 45. Such a cover is fully disclosed in U.S. Pat. Nos.5,885,172 and 6,132,324. The disclosures of these two patents areincorporated herein by reference in their entireties. Preferred coverpolymers include thermoset urethanes and polyurethanes, thermoseturethane ionomers and thermoset urethane epoxies.

In accordance to yet another aspect of the invention, as shown in FIG. 3golf ball 20 may have multiple layer core 12 a, 12 b and 12 c,surrounded by intermediate layer 14 and dimpled cover 16. Core layers 12b and 12 c may be an integral solid layer or discrete layers molded oneach other. Alternatively, both outer core layers 12 b and 12 c could bewound layers, or one of these two layers may be a wound layer, and theinnermost core 12 a may be liquid-filled.

While various descriptions of the present invention are described above,it is understood that the various features of the present invention canbe used singly or in combination thereof. Therefore, this invention isnot to be limited to the specifically preferred embodiments depictedtherein.

1. A golf ball comprising a cover layer encasing a subassembly, thesubassembly comprising a moisture vapor barrier layer encasing a core,wherein the moisture vapor barrier layer has a moisture vaportransmission rate of less than about 0.6 grams·mm/m²·day, and is formedfrom a composition comprising an elastomer and a double-bondvulcanizable rubber, and a thickness of less than 0.01 inch, wherein thecomposition is cured by infra red radiation or a combination of infrared and ultra violet radiations such that the properties of the coreremain unchanged after curing of the moisture vapor barrier layer. 2.The golf ball of claim 1, wherein the elastomer is halogenated,sulfonated, or both.
 3. The golf ball of claim 2, wherein the elastomeris halogenated, and comprises at least one of the following: less thanabout 3% reactive halogen; less than about 1 halogen atom per doublebond; a benzylic bromine functionality; or a branched styrenic block. 4.The golf ball of claim 1, wherein the elastomer comprises a conjugatedmulti-olefin or an iso-olefin.
 5. The golf ball of claim 1, wherein theelastomer is a copolymer of p-methylstyrene and isobutylene or abrominated copolymer of p-methylstyrene and isobutylene.
 6. The golfball of claim 1, wherein the composition further comprises a filler. 7.The golf ball of claim 6, wherein the filler is selected from a groupconsisting of leafing aluminum, mica flakes, micaceous iron oxideflakes, aluminum flakes, ceramic flakes, graphite flakes, and mixturesthereof.
 8. The golf ball of claim 1, wherein the composition furthercomprises at least one polymer selected from a group consisting ofvinyldiene chloride polymers and ionomers.
 9. The golf ball of claim 1,wherein the composition has a moisture vapor transmission rate of about0.001 grams·mm/m²·day to about 0.1 grams·mm/m²·day.
 10. The golf ball ofclaim 1, wherein the composition is a dynamically vulcanizablethermoplastic elastomer blend adhesive to diene rubbers.
 11. The golfball of claim 1, wherein the elastomer has a molecular weight of about20,000 to about 500,000.
 12. The golf ball of claim 1, wherein thecomposition forms a tortuous path against moisture vapor encroachment.13. The golf ball of claim 1, wherein the composition is applied in aform selected from a group consisting of liquid, latex, viscous liquid,semi-solid, solid, and in solvents.
 14. A golf ball comprising a coverlayer encasing a subassembly, the subassembly comprising a moisturevapor barrier layer encasing a core, wherein the moisture vapor barrierlayer has a moisture vapor transmission rate of less than about 0.6grams·mm/m²·day, a thickness of less than 0.01 inch, and is formed froma composition comprising an elastomeric homopolymer or copolymer thatcomprises about 0.2% to about 30% by weight of a conjugated multi-olefinhaving about 4 to about 14 carbon atoms, an iso-olefin having greaterthan 4 to about 7 carbon atoms, or a combination of the conjugatedmulti-olefin and the iso-olefin, and wherein the composition is cured byinfra red radiation or a combination of infra red and ultra violetradiations, and wherein the materials comprising the moisture vaporbarrier layer have higher cured temperatures than the softeningtemperatures of the materials comprising the core.
 15. The golf ball ofclaim 14, wherein the elastomeric copolymer comprises the conjugatedmulti-olefin and about 70% to about 99.8% by weight of the iso-olefin.16. The golf ball of claim 14, wherein the elastomeric homopolymer orcopolymer is amorphous and non-polar.
 17. The golf ball of claim 14,wherein the elastomeric homopolymer or copolymer is sulfonated,halogenated, or both; and wherein when halogenated, the elastomerichomopolymer or copolymer comprises at least one of the following: lessthan about 3% reactive halogen, less than about 1 halogen atom perdouble bond, a benzylic bromine functionality, or a branched styrenicblock.
 18. The golf ball of claim 14, wherein the elastomerichomopolymer or copolymer is a highly paraffinic hydrocarbon polymercomposed on long straight chain molecules containing only chain-endolefinic bonds.
 19. The golf ball of claim 14, wherein the elastomericcopolymer is a copolymer of p-methylstyrene and isobutylene or abrominated copolymer of p-methylstyrene and isobutylene.
 20. The golfball of claim 14, wherein the composition forms a tortuous path againstmoisture vapor encroachment.
 21. The golf ball of claim 14, wherein thecomposition is applied in a form selected from a group consisting ofliquid, latex, viscous liquid, semi-solid, solid, and in solvents. 22.The golf ball of claim 14, wherein the composition further comprises afiller selected from a group consisting of leafing aluminum, micaflakes, micaccous iron oxide flakes, aluminum flakes, ceramic flakes,graphite flakes, and mixtures thereof.